34 REPORT OF BOARD OF CONSULTING ENGINEERS) PANAMA CANAL.


 The Board has therefore found itself unable to recommend the sthmiian Commission's plan of 1901 for adoption by the Government, nor does it believe that any modification of that plan involving the use of lift locks should be adopted for the Panama Canal.

 PLAN OF MAJ. CASSIUS E. GILLETTE, U. S. ARMY.

 Among the papers submitted to the Board was un article by Maj. Cassius E. Gillette, Corps of Engineers, U. S. Army, which had been printed in the Engineering News of July 2, 1905. The article is entitled "The Panama Canal: Some serious objections to the sea-level plan." Under this heading occurs a general description of the various canal plans, ending with a description and recommendation by the author of a plan for a 100-foot summit level canal.
 He states that the engineering work is best which accomplishes the desired object at the least expense, and also that the cost of a canal is made up of the first cost, with that of operation and maintenance, and the cost of enlargement, the latter being a very important matter, as is shown by the history of all existing canals. Mention is made of the work being done on existing canals at the present time, and, in the opinion of the author, the best canal would be one that could be most easily enlarged. He thinks that the lock canal can be more easily changed and its capacity increased.
 He points out the advantages to be obtained by a canal with a high dam at Gatun, with reference to the elements of cost, time of construction, serviceableness, and ease of enlargement.
 In his opinion the question of sediment has not been heretofore sufficiently considered, and a description of the topographical features of the country as affecting sediment in the streams is given. The problem of disposing of sediment with a sea-level canal is, in the author's opinion, a serious one.
 It is alleged that large ships would have difficulty in navigating the present Atlantic entrance in the high winds which prevail in that vicinity, on account Of the sharp reverse curve necessary to enter the canal. He recommends practically a straight line for the canal from Gatun to deep water in Limon Bay, almost exactly the line which has been recommended by the Board in the sea-level plan.
 Objection is made to a high earth dam with a mi-asonry core at Gamboa. He suggests that a masonry core really converts a dam from an earth and rock structure into an inefficient masonry work, and that by the stoppage of all seepage water the rock and clay above the dam become thoroughly saturated, and the large proportion of soluble clay in its composition would make it, so far as pressure is concerned, heavier than water and increase the thrust.
 Major Gillette advocates a 100-foot summit level canal with a dam at Gatun. This will provide, in his opinion, a lake having an area of at least 100 square miles, subject to very slight fluctuations, and capable of settling for ages all the mud that the streams would bring into it; it would also supply all the water necessary for lockages and 'Would give a straigt channel between Bohio and Gatun.
 The proposed dam at Gatun is of earth, with a core of impervious material. To prevent seepage under the dam a method is suggested of using steel sheet piles driven to a depth of about (30 feet, and then to drive, in sections to bed rock immediately alongside of this sheeting, three-inch pipes, five to six feet apart, through which is to be forced cement grout.
 The project under discussion assumes a flight of three locks whose usable dimensions are 900 feet in length by (90 -feet in width, with lifts of 35, 35, and 30 feet. The author thinks the prejudice against locks of greater lifts than 35 feet, based upon difficulties inherent to gates with mniter sills, may be overcome by the use of floating caisson gates. The estimate for the flight of locks at Gatuin is $1,900,000. It is evident that this is for a single flight of locks.
 Many of the criticisms of the various suggested canal plans are the same which have been made in the sessions of thelBoard, whose plan is the logical development as a correction of the defects of previot~s pllans. The Board has adopted a line for the canal from Gatun to deep water which is practicallyv the one recommended by Major Gillette.
 His criticism of a high earth dam Nwith a masory core at Gamboa is worthy of attentionm. This matter has been considered by the Board, and in its plans the proposed estimate


34